This proposal is a resubmission of a request for renewal of the grant CA86191, first funded by NCI in 2000 under a special RFA Research in State and Community Tobacco Control Interventions, and then renewed in 2004. The Minnesota Adolescent Community Cohort (MACC) Study is a population-based cohort study that enrolled 4,825 youth (N=4,220 from Minnesota and N=605 from comparison states) aged 12 to 16. Participants were surveyed by telephone every six months since 2000-2001 about their tobacco use and related attitudes and beliefs, resulting in 14 data points over 15 rounds (MACC 1 includes Rounds 1-6, MACC 2 includes Rounds 8-15, Round 7 omitted due to funding gap). Additional funding was obtained to continue data collection for one additional round to specifically assess the short-term effect of Minnesota's statewide smoke-free air law on young adult smoking (MACC 3, Round 17; October 2008-March 2009). During Round 17 participants were age 18 to 25. We have requested ARRA administrative supplement funding to conduct Round 19 (October 2009-March 2010). The MACC cohort has a number of unique and important features. Unlike many studies of young adults, this cohort includes young adults who are not attending college as well as those who are attending college. National and state-level data show that tobacco use is more prevalent among young adults who are not attending college and studies are needed to assess how tobacco prevention programs and policies may affect this group. Detailed and frequent data have been collected on the MACC cohort regarding smoking attitudes and behaviors during adolescence. Using sophisticated data analytic techniques, we can provide more detailed information about the initiation and progression of tobacco use during adolescence and young adulthood than many previous studies (that have had lengthier intervals between data collection points). The large size of the MACC cohort enables us to examine differential effects of tobacco prevention programs and policies on subgroups of young adults, characterize patterns of tobacco progression with greater precision, identify less common patterns of progression, and distinguish age, cohort, and period effects. Finally, we have linked individual data on tobacco use to tobacco policies, school curricula, media exposure and other environmental characteristics of their communities over time. Using these linked data and extending this cohort will enable us to examine the long-term effects of adolescent exposure to various programs and policies on young adult tobacco use. We are also able to assess the effects of young adult exposure to new programs and policies (e.g., Minnesota's smoke-free air law) on smoking behavior and attitudes. We propose to follow the MACC cohort for an additional three annual observations from 2010-2011 to 2012-2013 (Rounds 21, 23, and 25; MACC 4). We plan to add measures concerning alcohol use and exposure to alcohol policies. Using these data, we will be able to examine the complex interplay between tobacco and alcohol use and the crossover effects of tobacco and alcohol policies in young adults.